1. Field of the Invention
The present invention relates to an intake control device, which changes a length of an intake conduit of an engine, to a straddle type vehicle incorporating such a control device, and to methods of setting the condition for changing and methods for changing the length of the intake conduit.
2. Description of the Related Art
Certain intake control devices mounted to straddle type vehicles, such as motorcycles, permit a length of an intake conduit to be changed from a predetermined length to a length different (e.g., shorter) than the predetermined length when an engine load (such as an engine speed or a throttle valve opening) reaches a predetermined threshold value, thereby varying an output characteristic of the engine (see Japanese Patent Publication No. 09-100720). Such an arrangement makes it possible to achieve high intake efficiency over a wide range of engine speed.